Through the state of art is known a top mechanism for the retractable top of an open automobile comprising a plurality of frame elements pivoted one after the other to be turnable relative to each other and which fold up outside the passenger space of the car and, on the other hand, can be stretched out over said passenger space. Said frame elements comprise a first frame element which is the foremost frame element on the free end of the top and which in the situation in which the top is extended over the car rests against a part belonging to the frame of the vehicle, such as the windshield beam. Furthermore, the frame elements include a second frame element, which is the frame element immediately adjacent to the first frame element. To the first frame element belongs a pair of first side rods, which are substantially longitudinal to the vehicle, on the side margin of the to. To the second frame element belongs, similarly, a pair of second side rods, which also are substantially longitudinal to the vehicle. The first and second side rods are arranged to be turnable relative to each other in a vertical plane. The top mechanism further comprises an operating rod, disposed to effect said turning of the first side rod in connection with the operation of extending, and folding up, the top mechanism. Top mechanisms of this type are known, for instance, through the references EP 0 400 376, DE 40 04 871, and DE 38 09 197.
The problem with top mechanisms known in the art is that when the first and second side rods have been extended into stretched-out position, in which they are end to end in relation to each other, the distance between the pivot point of the operating rod and the pivot point between the first and the second side rod, provided to enable their turning, i.e., the moment arm, becomes exceedingly short, thus considerably impeding control of the stretch-out turning motion in its ultimate stage as well as the corresponding motion at the beginning of the fold-up operation. The pivots and the rods are subject to major forces in these instances, inasmuch as the weight of the first frame element may be 10 kg and even more and the moment arm at disposal in order to effect its turning is almost nil. Moreover, owing to poor control of the turning of the foremost frame element in the ultimate phase of the stretch-on movement it is a frequent occurrence that the first top rib hits against the windshield beam (known as the slamming phenomenon), whereby undesirable pressure peaks are induced in the hydraulics operating the car top mechanism. This is disadvantageous from the user's viewpoint as well as that of the mechanism.
A further problem encountered in car top mechanisms of prior art is that when the top is in open position, that is, folded up, the end of the first side rod coincides in position with the end of the second side rod, in other words, the ends are in register because of the pivoting and they form an acute angle deviating grossly from the horizontal line; this sharp point may introduce a safety hazard in the event of collision with another vehicle. At the same time, the ends of the side rods lying one upon the other constitute a space-consuming structure. When the top is in retracted position, this structure must be covered with a protective cover, the configuration of which will, for the above reason, present a tall and unattractive structure standing out from the lines of the car body.